The five-hour launch readiness test, held at Florida's Cape Canaveral Air Force Station, went through full countdown procedures, including fueling, for the next Dragon test flight, which is slated for late April. It was designed to check out any potential issues with SpaceX's Falcon 9 rocket, Dragon and associated ground systems.

Dragon's upcoming flight will be the second – and, if all goes well, final – demonstration before operational cargo missions begin. During the test, SpaceX wants the capsule to dock with the orbiting lab and unload some supplies, just as it would during an actual cargo flight